WorkManager.getInstance().cancelAllWorkByTag() not stopping the periodic job

I believe the problem you are having here is answered in this duplicate question.

In summary, if you have a pending worker which hasn't started yet, the worker will be cancelled and will not run. However if the worker is already running, cancelling work does not terminate the worker in a hard fashion - it simply sets the state flag of the worker to CANCELLED, as explained in the docs. It is up to you to handle the cancellation inside your doWork and terminate the worker.

One way to do this is to put a few checks in your doWork method to check if the worker has been cancelled, by calling isStopped(). If isStopped is true, return from the method with a Result instead of continuing with the rest of the work.

While creating PeriodicWorkRequest i had added addTag() and to cancel task used same tag name, using this it cancel pending work. So my code is like:

PeriodicWorkRequest.Builder wifiWorkBuilder =
                            new PeriodicWorkRequest.Builder(FileUpload.class, 15,
                                    TimeUnit.MINUTES)
                                    .addTag("WIFIJOB1")
                                    .setConstraints(new Constraints.Builder().setRequiredNetworkType(NetworkType.METERED).build());
                    wifiWork = wifiWorkBuilder.build();
                    WorkManager.getInstance().enqueueUniquePeriodicWork("wifiJob", ExistingPeriodicWorkPolicy.REPLACE, wifiWork);

To stop job I am using:

WorkManager.getInstance().cancelAllWorkByTag("WIFIJOB1");

I've been checking the official Android docs: https://developer.android.com/reference/androidx/work/WorkManager

There are two types of work supported by WorkManager: OneTimeWorkRequest and PeriodicWorkRequest.

You can enqueue requests using WorkManager as follows:

 WorkManager workManager = WorkManager.getInstance();
 workManager.enqueue(new OneTimeWorkRequest.Builder(FooWorker.class).build());

A WorkRequest has an associated id that can be used for lookups and observation as follows:

WorkRequest request = new OneTimeWorkRequest.Builder(FooWorker.class).build();
 workManager.enqueue(request);
 LiveData<WorkStatus> status = workManager.getStatusById(request.getId());
 status.observe(...);

You can also use the id for cancellation:

WorkRequest request = new OneTimeWorkRequest.Builder(FooWorker.class).build();
 workManager.enqueue(request);
 workManager.cancelWorkById(request.getId());

And here you can see a different ways to cancel a enqueued work:

Maybe you also can try to cancel a enqueued or blocked job using the State of the job:

WorkStatus workStatus = WorkManager.getInstance().getStatusById(wifiWork.getId()).getValue();
        if(workStatus.getState() == State.ENQUEUED || workStatus.getState() == State.BLOCKED){
            WorkManager.getInstance().cancelWorkById(wifiWork.getId());

        }

I hope it helps you.